1. Field of the Invention
The present invention relates to a switching system for interconnecting two arbitrary terminals in a communication network, and more particularly to a time division digital switching system for use in a digital telephone switching system and in a data communication system.
The application of the present invention can be found in a communication network composed of a plurality of subsystems having a plurality of line circuits, for example, a plurality of telephones in the case of a telephone network or a plurality of computer terminals in the case of a data communication system.
2. Prior Art
For details of the time division digital telephone switching system, reference is made to the paper by G.L. Rainey and B.E. Voss entitled "SL-1: A Business Communications System with Digital Switching and Stored Program Control", CONFERENCE RECORD, on pages 432-1-1 through 432-1-6, of INTERNATIONAL SWITCHING SYMPOSIUM held Oct. 25 to Oct. 29, 1976, in Japan (Reference 1). In particular, in the telephone switching system shown in FIG. 4 of Reference 1, an outgoing path and an incoming path are separated in space in order to perform an encoded speech transmission between subscribers X and Y, and different time slots TS14 and TS15 are allotted to the subscribers so as to perform time division communication.
On the other hand, the configuration shown in FIG. 2 in the paper by A. Mack and B. Patrusky entitled "Time Division Digital Switch Matrix Technique Evaluation", CONFERENCE RECORD, on pages 40-1 through 40-7, of IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (June 19-21, 1972) is known as an example wherein the time division communication between the above-mentioned subscribers is performed through one interhighway without separating in space the outgoing path from the incoming path.
In this configuration, however, two time slots are used for the transmission and the reception, separately, of the communication between the subscribers.
In these prior art systems, the degree of multiplexing of communications, i.e., the maximum number of connections of connecting two arbitrary subscribers with each other simultaneously is half the number of time slots in a communication path, and consequently these systems are not advantageous in terms of the efficiency of multiplexing.